1. Field of the Invention
This invention relates to apparatus and method for testing the trueness of a circular cylindrical or conical specularly reflective surface of a piece to be tested.
2. Description Relative to the Prior Art
It is often desirable to test to a high degree of accuracy the surface of, for example, a cylindrical mirror or lens; a cylindrical surface of a bearing component formed of metal; or a conical surface of a metal component or of an optical element, such as an axicon. Such testing might include testing of the trueness of conformity of the actual surface to a perfect surface. The surface of a mirror is inherently specularly reflective. The surface of a lens reflects, specularly, a portion of the light incident on it unless, of course, special steps are taken to prevent such reflection. the surface of a metal bearing component is specularly reflective. Thus, it is possible to test a circular cylindrical surface of, for example, a mirror, a lens or a metal component, or a conical surface of, for example, an optical or metal component, by using light reflected by the surface.